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    Stepped fans and facies-equivalent phyllosilicates in Coprates Catena, Mars

    Grindrod, Peter M. and Warner, N.H. and Hobley, D.E.J. and Schwartz, C. and Gupta, S. (2018) Stepped fans and facies-equivalent phyllosilicates in Coprates Catena, Mars. Icarus 307 , pp. 260-280. ISSN 0019-1035.

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    Abstract

    Stepped fan deposits and phyllosilicate mineralogies are relatively common features on Mars but have not previously been found in association with each other. Both of these features are widely accepted to be the result of aqueous processes, but the assumed role and nature of any water varies. In this study we have investigated two stepped fan deposits in Coprates Catena, Mars, which have a genetic link to light-toned material that is rich in Fe–Mg phyllosilicate phases. Although of different sizes and in separate, but adjacent, trough-like depressions, we identify similar features at these stepped fans and phyllosilicates that are indicative of similar formation conditions and processes. Our observations of the overall geomorphology, mineralogy and chronology of these features are consistent with a two stage formation process, whereby deposition in the troughs first occurs into shallow standing water or playas, forming fluvial or alluvial fans that terminate in delta deposits and interfinger with interpreted lacustrine facies, with a later period of deposition under sub-aerial conditions, forming alluvial fan deposits. We suggest that the distinctive stepped appearance of these fans is the result of aeolian erosion, and is not a primary depositional feature. This combined formation framework for stepped fans and phyllosilicates can also explain other similar features on Mars, and adds to the growing evidence of fluvial activity in the equatorial region of Mars during the Hesperian and Amazonian.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Space and Planetary Science, Astronomy and Astrophysics
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    SWORD Depositor: Mr Joe Tenant
    Depositing User: Mr Joe Tenant
    Date Deposited: 23 Apr 2018 12:57
    Last Modified: 30 Jun 2020 08:37
    URI: http://eprints.bbk.ac.uk/id/eprint/22086

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